Worth buying to keep as a spare,because if it fails,the car will not start.
One of those parts that can be hard to find,yet can immobilise the car completely if it fails,so I bought it to keep as a spare..While I think it would be possible to by pass by connecting the cables to the battery direct,it may or may not work,deoending on how it affects the vehicles e.c.u. system,so for the relatively cheap price,in my opinion its worth buying to keep as a spare,